1990 15 hp Johnson won’t start, sort of sounds like it’s sucking air/leaking air

[David wright]

???----You will always see that " gap "----Was there from the day it left the factory !!

Well its a timing issue so why not try a new key my johnson 20hp flywheel does not have a gap that large or the movement that he seems to have

 

[David wright]

Well its a timing issue so why not try a new key my johnson 20hp flywheel does not have a gap that large or the movement that he seems to have

Although its very hard to see properly through photos and short videos

 

[flyingscott]

I am out. Until you do the proper tests you will get nowhere. The key way gap is fine a little experience would tell you that. The ops experience is not who I question.

 

[David wright]

I am out. Trying to Wade through this mess is tiring.

Giving up ?

 

[jitterbug127]

Purely novice

Does spark jump a 7//16" air gap? Done a dva test on the CDI box? Compression is?

It will jump about a 3/8” gap. I haven’t tried a 7/16” gap. Happy to try tonight. I’ve never heard of a DVA test so I haven’t done one. My compression is 96/100

 

[jitterbug127]

Fact are needed and heeded to.----You put fuel directly into the cylinder.----The motor did not fire up and bark at you.-----That means it is NOT a fuel issue.---So why would you spend an effort and put another carburetor on it ?----It is a spark / timing issue.----The wire from powerpack to top coil is orange with a blue stripe ??

I didn’t know that hitting fuel directly into the cylinders means that it’s not a fuel issue tbh. First time I’d ever done it, and wasn’t really sure of the logic. I was just doing what was suggested from another poster. I don’t know what diagnostic tests to do to check timing.

 

[jitterbug127]

Fact are needed and heeded to.----You put fuel directly into the cylinder.----The motor did not fire up and bark at you.-----That means it is NOT a fuel issue.---So why would you spend an effort and put another carburetor on it ?----It is a spark / timing issue.----The wire from powerpack to top coil is orange with a blue stripe ??

I also have the blue/orange wire on the bottom I think: I’m at work not but will check when I get home.

 

[jitterbug127]

The man has to do some listening and trouble shooting.----No more effort from me to try and help on this simple issue..

I’m happy to listen, I am not completely sure what troubleshooting tests to do from here. I do appreciate your effort to this point! Thank you.

 

[jitterbug127]

I am out. Until you do the proper tests you will get nowhere. The key way gap is fine a little experience would tell you that.

Thanks for your help. I am honestly not sure what the proper tests to do from here. I have minimal experience with key ways, so I wouldn’t know if it was broke or not.

 

[flyingscott]

Thanks for your help. I am honestly not sure what the proper tests to do from here. I have minimal experience with key ways, so I wouldn’t know if it was broke or not.

Buy a manual. Rent a compression. Tester. Start there. Those motors had trulblesome ignition modules.

 

[flyingscott]

Op would be better off taking his motor to a dealership.

 

[flyingscott]

Giving up ?

6 pages and the motor is not running? Time to go to a dealer

 

[jitterbug127]

Sounds great thank you! I do have a compression tester. I have really considered taking to dealership. I am getting more confused the more I do

 

[jitterbug127]

Folks i sincerely do appreciate all your help. I am happy to admit that I am a complete moron when it comes to these motors. I’m willing to take on advice and learn. Sometimes when I get 10 people with 10
Opinions it’s hard to decipher which route to take. I know the very basics of trouble shooting so I’m sure there are plenty of more tests ti learn.

 

[racerone]

The sky is BLUE and grass is GREEN-----Therefor orange blue stripe goes to top coil and orange green to the bottom coil.-----

 

[Nordin]

Please, please David Wright forget about a bad flywheel key.
That key is order, the gap at the top of the wheel is from factory.
The length and height of the key will set the flywheel in right position.
Torque the flywheel nut to right value and start to troubleshoot the ignition system.
As compression are 96/100 it should run.
Check the stator output voltage, it should be 150+VDC measured with a DVA meter or a VOM with a DVA adapter.
Check the trigger output, it should be 0,5+VDC.
Check if spark can jump 3/8 in or more in atmosphere.
Clean the carb and set the air/fuel mixture screw 1,5 turn out from lightly seated.
Check the throttle pick up adjustment, the throttle roller should start to touch the cam at the mark at the cam.

 

[jitterbug127]

The sky is BLUE and grass is GREEN-----Therefor orange blue stripe goes to top coil and orange green to the bottom coil.-----

Once again racer is always right. That’s rule #1 I need to follow. This is exactly right! I got it to cough this morning. I had the orange wires with the blue line and orange with green line backwards. Spark problem that I caused fixed! .

Now I’ve got a motor that quit running acting like it was starving for fuel. I’m gonn buy new gas today and try again

 

[David wright]

Once again racer is always right. That’s rule #1 I need to follow. This is exactly right! I got it to cough this morning. I had the orange wires with the blue line and orange with green line backwards. Spark problem that I caused fixed! .

Now I’ve got a motor that quit running acting like it was starving for fuel. I’m gonn buy new gas today and try again

Wow awesome moving forward hope you get everything sorted out

 

[OptsyEagle]

In Summary for future reference:

When you motor doesn't start, put a little fuel in the cylinder holes and if it coughs but then dies it is most likely a fuel deliver problem. Carb, fuel pump, air leak, fuel line or fuel tank. If it coughs, starts and then runs great afterwards, it is probably a choke issue. Maybe link and sync.

If it does nothing like yours did, it is a spark or compression issue. Since your compression numbers were fine the problem was then narrowed down to a spark issue. Since you had good spark with an air tester it was either a spark timing or your spark plugs were bad. Since you changed the plugs you should now know your problem was a spark timing problem. You see how that works. It's not difficult.

I did ask a few posts back if you might have reversed the spark plug leads, which would put your spark timing at the worst possible point, bottom dead center. Reversing spark plug leads can happen at the plugs or in your case from the wires from the flywheel. Either will keep the motor from running. Now you know.

Anyway, glad it is fixed and I assume you will be able to diagnose these problems better the next time...and there will be a next time. The fun with older motors never ends.

 

[jitterbug127]

In Summary for future reference:

When you motor doesn't start, put a little fuel in the cylinder holes and if it coughs but then dies it is most likely a fuel deliver problem. Carb, fuel pump, air leak, fuel line or fuel tank. If it coughs, starts and then runs great afterwards, it is probably a choke issue. Maybe link and sync.

If it does nothing like yours did, it is a spark or compression issue. Since your compression numbers were fine the problem was then narrowed down to a spark issue. Since you had good spark with an air tester it was either a spark timing or your spark plugs were bad. Since you changed the plugs you should now know your problem was a spark timing problem. You see how that works. It's not difficult.

I did ask a few posts back if you might have reversed the spark plug leads, which would put your spark timing at the worst possible point, bottom dead center. Reversing spark plug leads can happen at the plugs or in your case from the wires from the flywheel. Either will keep the motor from running. Now you know.

Anyway, glad it is fixed and I assume you will be able to diagnose these problems better the next time...and there will be a next time. The fun with older motors never ends.

This is the best explaination I’ve ever seen for this! I’m saving it to my phone tank you!

As far as the wires being crossed I only checked the black wires to make sure they didn’t go to the wrong cylinders. The orange wires didn’t even cross my mind.